Our research deals with the synaptic mechanisms and function organization the vertebrate retina uses to process visual information. Of particular interest are the adaptation mechanisms that regulate photoreceptor threshold, speed of response, and dynamic range. Intracellular and suction electrode recording will be used in conjunction with early receptor potentials to directly determine the relationships between visual pigment concentration and sensitivity. Responses determined against various backgrounds and during dark adaptation will be used to test the equivalence of real lights and "dark" lights. The physiological basis of retinal "network" contributions to visual adaptation will be examined. Using intraretinal recording of K+ om the rat retina we will determine whether potassium is the desensitizing substance which controls "network adaptation". Other studies will seek to isolate and identify the contributions of the Muller cells to various components of the transretinal ERG and to develop and utilize ion-specific electrodes for quantitative analysis of the alterations in extracellular activities of essential ions throughout the retina in light and dark adaptation. We also intend to analyze the anisometropic amblyopia, which results from rearing cats wearing high power soft contact lenses, at the behavioral, cellular and systems levels. Various tests of a physiological hypothesis of amblyopia wil be performed on our cat model. These will include the effects of ablating area 17 of cortex in normal and amblyopic cats, the use of neurotoxins which may selectively affect Y-cell pathways, electrophysiological recording at different brain loci, and the use of new anatomical techniques that label the regions of brain activated by particular stimuli. We hope to follow this by investigating new treatments of the anisometropic amblyopia. Occlusion, penalization and stimulation therapies will be compared.